Neuronal loss is involved in neurodegenerative disorders such as Parkinson's disease, Huntington's disease, Alzheimer's disease, amyothrophic lateral sclerosis, and multiple sclerosis, stroke, and hearing loss. None of the drugs currently available is satisfactory in treating these disorders or even in slowing their progression. Some even produce undesirable side effects, such as motor fluctuations and dyskinesias in Parkinson's disease. See, e.g., Quinn, et al., Neurology, 1998, 51, S25-29.
Thus, there is an urgent need to develop effective neuroprotective drugs.